The Center for Clinical Epidemiology and Biostatistics (CCEB) and the Department of Obstetrics and Gynecology of the University of Pennsylvania Perelman School of Medicine (OB/GYN), collaborating with the Department of Pediatrics of the Children's Hospital of Philadelphia (Neonatology), propose to continue and enhance an innovative, rigorous, and highly successful two- to three-year research training program for clinicians in reproductive epidemiology. This training program attracts trainees from across the US and its graduates are placed in academic institutions nationwide, resulting in a program of high impact. The training program consists of required courses in epidemiology, clinical research methodology, biostatistics, and reproductive epidemiology; elective courses relevant to the trainees' methodologic interests; journal clubs and clinical research conferences conducted by participating faculty in the CCEB, OB/GYN, and the Neonatology; extensive independent readings; instruction in the responsible conduct of research; a professional development series; grant writing and grant development experiences; and the completion of an independent research project in reproductive epidemiology. The program: 1) trains clinicians to be rigorous and independent academic investigators able to use the range of approaches available in epidemiology to address research issues in reproductive medicine, women's health, and/or neonatology related to the etiology, prognosis, prevention and early detection, treatment, clinical economics, technology assessment, medical decision making, and quality of patient care; 2) provides closely mentored research experiences with faculty preceptors in clinical epidemiology, and obstetrics and gynecology; and 3) strengthen the links between traditional epidemiology, obstetrics and gynecology, pediatrics, and women's health. Trainees matriculate in the Master of Science in Clinical Epidemiology (MSCE) program. Strengths of the proposed program are: 1) the long history of successful research training programs in the CCEB, and OB/GYN; 2) the collaborative links that have been forged among the faculty of these academic entities; 3) the comprehensive course offerings and research programs that are available to trainees; and 4) an extensive set of experienced program directors and faculty preceptors with successful training records. In addition, the availability of the broad range of rich expertise of the faculties in the CCEB, the Department of Obstetrics and Gynecology, and the Division of Neonatology; numerous existing large databases that can be used for research projects and training; a broad array of specialized analytic capabilities available for clinical studies (e.g., clinical trials, cse-control, cohort research, etc.); and the faculties' commitment to collaborative research and training, combine to provide an ideal environment for this training program. Finally, Penn and the PSOM promote an academic environment in which basic and clinical research are encouraged and viewed as attractive career paths for physicians.